JPH0555739A - Heater chip and fine lead joining method utilizing the same - Google Patents

Abstract

PURPOSE:To provide a heater chip for joining a fine lead covered with a heat sublimative material for insulation to a solder deposited connecting area on a printed circuit board and a fine lead joining method using the same which eliminates defective sublimation of insulator of the fine lead and insufficient deposition of solder. CONSTITUTION:A fine lead joining method utilizes a heater chip 1 provided with a holding groove 2 having an arcuate bottom in the same diameter as an outer diameter of a fine lead 8 at the central area for holding a fine lead 8 at the end part thereof and also transmitting heat thereto and a solder-up groove 3 provided in the direction transverse to the holding groove and almost in the same depth thereas at the central area of the holding groove 2 and a heater head provided with the heater chip 1 at the end of the bending area of the bending heating conductor 6 to feed a pulse current having controlled an amplitude or pulse duration to the heater head 5 in order to control heating temperature and thereby realizes reflow solding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater chip in which a thin wire, which is insulation-coated with a heat sublimable material, is joined by reflow soldering to a soldered connection portion of a printed wiring board, and a thin wire using the heater chip. Regarding the joining method.

In recent years, with the rapid progress of semiconductor integrated circuits, electronic circuit devices have been improved in performance, reliability, size, and economy. As for mounting on a printed wiring board that constitutes a circuit, extremely high-density mounting has come to be performed.

However, the products are always changed, and circuit changes occur in the printed wiring board.
This circuit change involves cutting the printed wiring, adding wiring with a wire material, replacing parts, adding, deleting, etc., but it is required to perform this change with high reliability.

[0004]

2. Description of the Related Art FIG. 3 shows an example of conventional wire joining. Here, a case where wiring is added by a wire material on a printed wiring board due to a circuit change will be described.

A conventional example of wire joining is as shown in FIG. 3, in which a thin wire 8 of an insulating covered wire is attached to a connecting portion 99 such as a connecting land or a through hole of a printed wiring board 9 to which solder 91 has already been applied. The end portion is placed, and the heater head 55 is pressed from above and heated to perform reflow soldering.

A heater chip at the tip of the heater head 55
15 is a thin wire 8 so as to suppress the thin wire 8 and transfer heat efficiently.
There is a gutter-shaped restraining groove 25 in contact with. The thin wire 8 is a thin copper wire that is insulation-coated with a heat-sublimable insulating material. When heated by contact with the heater chip 15, the insulation coating 82 is sublimated and removed, and the core wire 81 is exposed. And then the connection
The deposited solder 91 of 99 is melted and also deposited on the surface of the core wire 81 for reflow soldering.

[0007]

However, in some cases, the sublimation of the insulating coating 82 of the thin wire 8 is incomplete, and the solder 91
Will be insufficiently adhered. Holding groove 25 of heater chip 15
If the surface of the product is soiled due to adhesion of solder residue, etc., additional soldering will be insufficient. There were problems such as.

In view of the above problems, it is an object of the present invention to provide a joining method which eliminates the occurrence of sublimation failure of insulating coating of fine wires and insufficient solder deposition.

[0009]

The above-mentioned object is, as shown in FIGS. 1 and 2, [1] a connection portion 99 on the printed wiring board 9 to which a solder 91 is attached.
A heater chip 1 for joining a thin wire 8 insulation-coated with a heat sublimable material by reflow soldering, in which heat is suppressed while suppressing the thin wire 8 at the tip, and the outer diameter of the thin wire 8 is the same at the central portion This is achieved by using the heater chip 1 of the present invention in which, in addition to the holding groove 2 having an arc-shaped bottom portion, the holding groove 2 is provided with a solder rising groove 3 orthogonal to the holding groove 2 and having substantially the same depth in the central portion thereof. .. [2] Similarly, in addition to the holding groove 2 having an arc-shaped bottom portion having the same diameter as the outer diameter of the thin wire 8 in the center portion for transmitting heat by holding the thin wire 8 at the tip portion, one end is also passed through the holding groove 2. The heater chip 11 of the present invention having the upward gas vent hole 4 having the other end communicated with the outside can also be used. [3] Further, the heater chips 1 and 11 having the above-mentioned shape are used for heating by applying a pulse current whose amplitude or pulse width is controlled to the heater head 5 using the heater head 5 provided at the folded tip of the folded heating conductor portion 6. This is achieved by the fine wire bonding method of the present invention in which temperature control is performed and reflow soldering is performed.

[0010]

In other words, since the heater chips 1 and 11 are additionally provided with the solder rising groove 3 and the gas vent hole 4 in addition to the holding groove 2, the gas in which the insulating coating 82 of the fine wire 8 sublimes is produced in all cases. Since it dissipates easily, the core wire 81 can be surely exposed and sufficient solder deposition can be performed.

In the heater chip 1, since the solder rising groove 3 is provided in the groove of substantially the same depth, orthogonal to the central position of the restraining groove 2, the sublimation gas in the central portion where the gas is most difficult to dissipate is easy. It is possible to dissipate in a good soldering.

Since the gas vent hole 4 is provided upward in the heater center 11 so as to communicate with the holding groove 2, sublimation gas can be emitted from the inside other than the front and rear of the holding groove 2 if properly provided in the central portion or inside position. The core wire 81 is completely exposed because it escapes and stays and the incomplete sublimation disappears, so that sufficient solder deposition is surely performed.

However, since the temperature at which the insulating coating 81 is sublimated is high and soldering at high temperature cannot be performed, the temperature control of the heater head 5 provided with the heater chips 1 and 11 must be accurate and quick. I won't.

Therefore, the heating conductor portion 6 is folded back to improve the heating efficiency, and the heater head 5 is provided with the heater chips 1 and 11 at the tip of the folded back portion. Amplitude control or pulse width control of the temperature control enables rapid temperature change and constant temperature accuracy and stability.

Thus, according to the present invention, it is possible to provide a joining method that eliminates the occurrence of sublimation failure of the thin wire insulating coating and insufficient solder deposition.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in the drawings. Throughout the drawings, the same reference numerals denote the same objects. FIG. 1 shows an embodiment of the present invention, (a) is a heater chip, (b) is a configuration diagram of a joining method, and FIG. 2 shows a heater chip of another embodiment of the present invention.

In the present embodiment, when wiring is added by a wire material on the printed wiring board due to a circuit change, a fine wire coated with a thermally sublimable insulating coating is used, and the solder 91 on the printed wiring board is already removed. Reflow soldering is performed on the attached connecting portion 99.

One embodiment has a construction of the joining method shown in FIG. 1 (b), in which the end portion of the thin wire 8 is connected to the connection portion 99 to which the solder 91 on the printed wiring board 9 is adhered. The heater chip 1 at the tip of the heater head 5 is placed on top of it, held down, heated, and reflow soldered.

As shown in FIG. 1 (a), the heater head 5 has a structure in which the heating conductor portion 6 is folded so as to enhance the heating efficiency, and the heater chip 1 is provided at the tip of the folded portion. The heater chip 1 uses a molybdenum material with less surface contamination, and the heater chip 1 holds the thin wire 8 and transfers heat. The holding groove 2 has an arc-shaped bottom portion having the same diameter as the outer diameter of the thin wire 8 at the center of the tip. Further, a solder rising groove 3 of the same shape is provided in the central portion of the restraining groove 2 at a depth substantially the same as that of the solder rising groove 3 at a right angle.

The thin wire 8 is a copper 0.2, 0.16, 0.12 mmφ core wire.
81 is an insulating material of polyurethane having a thickness of about 10 μm, and nylon as a protective layer having a thickness of 1 μm is coated with an insulating coating 82, and a heater head 5 having a different size is used according to the wire diameter.

In this fine wire 8, the insulating coating 82 can be completely sublimated at 430 ° C. for 2 seconds or less, and the core wire 81 can be soldered at 260 ° C. for 2 to 3 seconds. Therefore, the heater chip 1
In order to quickly and accurately control the temperature of (1), a pulse current is applied from the pulse power source 7 with pulse width control to the heating conductor portion 6 to heat it. One end of the thermocouple 71 is welded and fixed to the heater chip 1 to detect the temperature, which is connected to the pulse power source 7 to react to the set temperature at a high speed and maintain the accuracy.

In this thin wire joining, when the thin wire 8 is pressed against the connecting portion 99 by the holding groove 2 of the heater chip 1, the thin wire 8 is heated to the sublimation temperature and maintained for a little less than 2 seconds to completely sublimate the insulating coating 82. Then, the pulse width is rapidly narrowed and the temperature is lowered to an appropriate temperature for soldering, and the temperature is maintained for less than 3 seconds to melt the solder 91 deposited on the connection portion 99 and deposit it on the exposed core wire 81 for reflow soldering.

At this time, the thermal sublimation gas of the insulating coating 82 is transmitted through the restraining groove 2 and is discharged from the left and right after passing through the solder rising groove 3 in the central portion and in the central portion, and is scattered and removed almost completely without retention, and the core wire is removed. 81 can be completely exposed.

In another embodiment, the heater chip 11 is shaped as shown in FIG. 2, and a gas vent hole 4 is provided in place of the solder rising groove 3 of the heater chip 1. These gas vent holes 4 are connected to the central portion along the edge of the groove 2 and to the front and back thereof, and the other end to the inside of the folded portion of the heating conductor 6 and the front and rear surfaces thereof. The gas vent hole 4 is provided so that the sublimated gas can also escape from the gas vent hole 4 without staying and completely dissipate.

The above-mentioned embodiments are merely examples, and the shape, size, and material of each part are not limited to those described above.

[0026]

As described above, according to the present invention, the occurrence of sublimation failure or insufficient solder deposition of the insulating coating of thin wires is almost eliminated, the heater chip is prevented from being contaminated, and rebonding is almost eliminated. The effect is remarkable.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention (a) a heater chip (b) a joining method

FIG. 2 is a heater chip according to another embodiment of the present invention.

FIG. 3 A conventional example of wire joining

[Explanation of symbols]

1,11,15 Heater chip 2,25 Holding groove 3
Solder rise groove 4 Gas vent 5,51,55 Heater head 6
Heating conductor 7 Pulse power supply 8 Fine wire 9
Printed wiring board 71 Thermocouple 81 Core wire 82
Insulation 91 Solder 99 Connection

Claims (3)

[Claims] 1. A fine wire insulatively coated with a thermal sublimation material on a connecting portion (99) on a printed wiring board (9) to which a solder (91) is adhered.
Heater chip for joining (8) by reflow soldering
(1) The thin wire (8) is held at the tip to transfer heat, and the thin wire (8) is placed at the center.
In addition to the restraining groove (2) having an arcuate bottom having the same diameter as the outer diameter of the holding groove, a solder rising groove (3) having substantially the same depth is provided in the center portion of the restraining groove (2) orthogonally to this. A heater chip characterized by that. 2. A fine wire insulatively coated with a thermal sublimation material on a connection portion (99) on a printed wiring board (9) to which a solder (91) is adhered.
Heater chip (1) that joins (8) by reflow soldering
1), the thin wire (8) is held at the tip to transfer heat, and the thin wire (8) is placed at the center
In addition to the restraining groove (2) having an arcuate bottom with the same diameter as the outer diameter of the above, an upward venting hole (4) with one end passing through the restraining groove (2) and the other end communicating with the outside is provided. A heater chip characterized by being drilled. 3. A heater head (5) comprising the heater chip (1, 11) according to claim 1 or 2 at the folded back end of a folded heating conductor portion (6), the heater head (5) being used. A fine wire joining method, characterized in that a heating current is controlled by applying a pulse current whose amplitude or pulse width is controlled to the reflow soldering.